Processes and intermediates for deoxyfluorocytidine



United States Patent ()fi ice 3,040,020 Patented June 19, 1962 No Drawing. Filed June 3, 1959, Ser. No. 817,736

3 Claims. (Cl. 260-2115) This invention relates to novel chemical methods, and to novel intermediates therefor. More particularly, in one of its aspects, it relates to methods for the preparation of l-(2-deoXy-D-ribofuranosyl)-5-fluorocytosine, especially 2-deoXy-5-fluorocytidine and its a-anomer, and to intermediates useful in practicing said methods. 2'- deoxy-S-fluorocytidine is a known compound, useful inter alia as an antibacterial and antifungal agent and as an antimetabolite. In another of its aspects, the invention relates to methods of preparing S-fluorocytosine, and to intermediates useful in practicing said methods. S-fiuorocytosine is also a known compound, useful inter alia as an antimetabolite and as an intermediate for the preparation of other useful compounds, e.g. 2'-deoXy-5-fiuorccytidine.

In one of its comprehensive embodiments, the invention relates to processes of making l-(2'-deoxy-D-ribofuranosyl)--fluorocytosine which comprise reacting S-fluorocytosine with a mercuric salt, thereby forming S-fluorocytosine-monomercury, reacting the latter with 2-deoxy-3, S-diaroyl-D-ribofuranosyl halide, thereby forming l-(2'- deoxy-3,5'diaroyl-D-ribofuranosyl) 5 fluorocytosine, and hydrolyzing the latter. Especially preferred in the above processes are those embodiments wherein the aryl portion of the aroyl radicals referred to contains not more than ten carbon atoms and is selected from the group consisting of phenyl (lower alkyl)phenyl, (lower alkoxy) phenyl, halophenyl and nitrophenyl; e.g., p-tolyl or pchlorophenyl; and the halide referred to is chloride or bromide. Illustrative mercuric salts of organic carboxylic acids which can be employed include mercuric formate, mercuric acetate, mercuric benzoate and the like. Mercuric chloride can also be used. However, mercuric acetate is preferred. A preferred embodiment of this branch of the invention relates to a process which comprises reacting 5-fluorocytosine with mercuric acetate, thereby forming S-fluoro cy-tosine-monomercury; reacting the latter with 2-de0Xy-3,5-di(p-toluoyl) -D-ribofluranosyl chloride, thereby forming 1-(2-deoxy-3',5[p-toluoyl]-D-ribofuranosyl)-5-fluorocytosine; and hydrolyzing the latter with alkali, thereby forming l-(2'-deoxy-D-ribofuranosyl)-5-fluorocytosine.

In another of its comprehensive embodiments, the invention provides a process of making S-fluorocytosine, useful as a starting material in the processes described above, which comprises reacting S-fluorouracil with a chlorinating agent, thereby forming 2,4-dichloro-5-fluoropyrimidine; reacting the latter with ammonia, thereby forming 2- chloro-4-amino-5-fiuoropyrimidine; and hydrolyzing the latter. A preferred embodiment of this branch of the invention comprises reacting S-fiuorouracil with phosphorus oxychloride in the presence of an acid acceptor, preferably a tertiary organic base, thereby forming 2,4- dichloro-S-fiuoropyrimidine; reacting the latter with ammonia under mild conditions (e.g. by reacting at room temperature a solution of 2,4-dichloro-5-fiuoropyrimidine in a lower alkanol, such as ethanol, with aqueous ammonia, which under these conditions can be present even in excess), thereby forming 2-chloro-4-amino-5-fiuoropyrimidine; and treating the latter with a strong mineral acid (e.g. concentrated hydrochloric acid), thereby forming S-fluorocytosine.

In an embracive embodiment, therefore, the inventlon provides processes of making l-(2'-deoXy-D-ribofnranos yl)-5-fiuorocytosine which comprise chlorinating S-fluorouracil, thereby forming 2,4-dichloro-S-fluoropyrimidine; reacting the latter with ammonia, thereby forming 2- chloro-4-amino-S-fluoropyrimidine; hydrolyzing the latter, thereby forming S-fiuorocytosine; reacting the latter with a mercuric salt, thereby forming S-fluorocytosine-monomercury; reacting the latter with 2-deoxy-3,5-diaroyl-D- ribofuranosyl halide, thereby forming l-(2'-deoxy-35- diaroyl-D- ribofuranosyl)-5-fluorocytosine; and dearoyl ating the latter.

The processes described above are illustrated graphically in the following diagrammatic flowsheet, wherein the symbol R represents an aryl radical containing not more than ten carbon atoms selected from the group consisting of phenyl, (lower alkyl)-phenyl, (lower alkoXy)phenyl, halophenyl and nitrophenyl:

FLOWSHEET fi) O1 l 'THz HN 3 l N F N F J i ml a N N H r r N I F N i F O m N N H I Hg-OH (IV) (W N F o l [I 0% B00011; HOCH: O N

ll I C(fiR H (VI) (VII) The first stage of the embracive embodiment referred to above (i.e. l li) comprises dichlorinating S-fluorouraoil (I). This stage is conveniently effected by treating 5- fiuorouracil with a conventional phosphorus-containing chlorinating agent. Preferably phosphorus oxychloride is employed, but phosphorus pentachloride can also be employed. The reaction is conveniently eifected by heating the reactants together, while agitating well, in the presence of a tertiary organic base as acid acceptor, e.g. dimethylaniline or diethylaniline. An inert organic solvent can be employed if desired, but its use is not necessary.

The second stage (II- 111) is conveniently efiected by dissolving 2,4-dichloro-5-fiuoropyrimidine (II) in a lower alkanol solvent, conveniently ethanol, and allowing the solution to stand with aqueous or alcoholic ammonia until the amination reaction has proceeded to the desired extent. The reaction is followed by volumetric titration of chloride ion produced by the reaction, and the end point is signalized by determination or" one atom-proportion of chloride ion in the reaction mixture.

The stage (HI-a IV) is effected by hydrolyzing 2-chloro- 4-amino-5-fluoropyrimidine to produce S-duorocytosine. A convenient method comprises hydrolysis with a strong mineral acid, preferably by heating the starting material a a s e 3 with concentrated hydrochloric acid. The reaction is carried on until the desired degree of hydrolysis has taken place. A convenient method of determining the end point is by means of ultraviolet spectrophotometry, using the absorption characteristics of an authentic specimen of S-fluorocytosine as a standard.

The next stage (IV- V) is conveniently effected by heating a solution of S-fiuorocytosine in water with a solution of mermuric acetate in methanol. Mercun'c chloride can also be employed. Also, mercuric salts of other organic acids can be employed, e.g. mercuric benzoate. The 5-fiuorocytosine-mono-mercury produced is difficult to obtain in filterable form. It can be converted to filterable form by boiling with water. It will be understood that the monomercury product obtained is more or less hydrated, as shown by its alkaline reaction to litmus. A portion of the combined water can be removed by drying.

In efiecting the transformation (V VI), S-fluorocytosinemonoznercury is first suspended in an inert organic solvent, e.g. benzene, toluene or dimethylforamide. When toluene is employed, it is usually convenient to distill ofi a portion of the solvent in order to insure removal of water. The 'aroylating agent, conveniently 2-deoxy- 3,5-di(.p-toluoyl) -D-ribofuranosyl chloride or 2-deoxy- 3,5 di(p chlorobenzoyl)-D-ribofuranosyl chloride, is added to the solution, and the reactants are heated until no further dissolution of the mercury compound is observed.

The iinal step, dearoylation (VI-9W1), can be effected by conventional saponification methods using alcoholic alkalies, e.g. ethanolic sodium hydroxide, methanolic sodium methoxide, ethanolic ammonia, ethanolic barium ethylate, and the like.

Those skilled in the art will understand that, whereas the compound S-fiuorocytosine-monomercury represented graphically above in Formula V is shown in a particular monomeric form, the compound can also exist in tautomeric and polymeric forms, as well as in forms which are hydrated to greater or less degree. All of these forms are included in the invention. Thus, Formula V represents the compound in a full hydrated form and as containing only a single mercury atom, i.e. in this instance a monomeric compound; but the invention also includes less hydrated forms, and dimeric and polymeric forms containing permolecule two or more mercury atoms, respectively; however, still containing mercury in the ratio of one atom per pyrimidine nucleus.

The starting material S-fluorouracil (Formula I) is a known, compound and does not per se form part of the present invention. The 2-deoxy-3,S-diaroyl-D-ribofuranosyl halides required as reactants for converting compounds of Formula V to those of Formula VI have also been described prior to the present invention, and do not per se form a part thereof. For convenience of reference, the preparation of 2-deoxy-3,5-di(p-toluoyl)-D- ribofuranosyl chloride, employed as a reactant in Examples 5 and 6 below, is described herein:

PREPARATION OF 2-DEOXY-3,5DI(p-TOLUOYL)- D-RIBOFURANOSYL CHLORIDE 13.6 g. of Z-deoxy-D-n'bose was dissolved in 245 ml. of methanol and 27 ml. or" a 1% solution of anhydrous hydrogen chloride in methanol was added. The mixture was allowed to stand for 20'minutes at 27 C. and then was stirred with 5 g. of silver carbonate until it no longer reacted acidic. The silver salts were removed by filtration withsuction and were washed with methanol. The combined filtrate and washings were evaporated in a vacuum as far as possible, 20 ml. pyridine was added and the solution was again evaporated in a vacuum in order to remove the last traces of methanol.

The syrupy residue of 2-deoxy-l-methyl-D-ribofuranoside was then dissolved in 80 ml. of dry pyridine, the solution was cooled to approximately 0 C., and 34 g. of

dp-toluoyl chloride was added in portions while maintaining the temperature below 20 C. After the addition of the chloride, the temperature was allowed to rise to 4045 C. and kept there for two hours. The mixture was diluted with 500 ml. of water, the oily precipitate was shaken out with 200 ml. of ether, the ether layer was washed successively with water, KHSO solution, water, KHCO solution, and water again, and was then dried over anhydrous sodium sulfate. The ether was re moved by evaporation in a vacuum and the remaining syrup of l-deoxy-3,5-di(p-toluoyl}-1 methyl-D-ribofuranoside was dissolved in 20 ml. of acetic acid while Warming. The solution was cooled to below 10 C., and 80 ml. of a saturated solution of anhydrous hydrogen chloride in acetic acid was added at 0-l0 C. Anhydrous hydrogen chloride was conducted into the solution for a few minutes, wh reupon the product crystallized rapidly, filling the whole vessel. After 10 minutes, the crystals were 1 filtered by suction. The filter cake was slurried with 100 ml. of ice-cold absolute ether, the slurry was filtered with suction, and the filter cake was rapidly transferred into a vacuum desiccator and dried in a vacuum over soda lime at room temperature, yielding dry, crystalline 2- deoxy-3,5-di(p-toluoyl)-D-ribofuranosyl chloride.

Similarly for convenience of reference, the preparation of 2-deoxy-3,5-di(p-chlcrobenzoyl)-D-ribofuranosyl chloride, employed as a reactant in Example 7 below, is described herein:

PREPARATION OF Z-DEOXY-TS -DHp-CHLORO- BENZOYL) -D-RlBOFURANGSYL CHLORIDE 3.5 g. of dry crystalline 2-deoxy-D-ribose was dissolved in 63 m1. of methanol and 7 ml. of a 1% solution of anhydrous hydrogen chloride in methanol was added. The mixture was allowed to stand for 20 minutes at 27 C. Five g. of silver carbonate was added and the mixture was stirred thoroughly. The silver salts were removed by filtration. The methanol was distilled off in a vacuum as completely as possible. The residue was diluted with 10 ml. of anhydrous pyridine, and the solution was again evaporated in a vacuum in order to remove the last traces of methanol.

The oily residue, crude 1-methyl-Z-deoxy-D-riboiuranoside, was dissolved in 20 ml. of anhydrous pyridine and 8 ml. of p-chlorobenzoyl chloride was added in portions while cooling with ice water to mm'ntain the temperature between 20 and 40 C. The mixture was allowed to stand overnight, water and methylene chloride were added, the layers were separated, and the methylene chloride layer was washed successively with KHSO solution and water, dried over sodium sulfate and finally evaporated in a vacuum.

The syrupy residue, 1-methyl-2-deoxy-3,5-di(p-chloro benzoyl)-D-ribofuranoside, was dissolved in 20 ml. of acetic acid and 50 ml. of a cold saturated solution of anhydrous hydrogen chloride in 100ml. acetic acid was added at 1015 C. Crystallization of 2-.deoxy-3,5-di(pchlorobenzoyl)-D-ribofuranosyl chloride occurred.

The invention is further disclosed in the following examples, which are illustrative but not limitative thereof.

Example 1.2,4-Dichl0r0-5-Flu0i'0pyrimidine (II) A mixture of 104 g. (0.8 mol) of S-fluorouracil (Formula I), 1472 g. (9.6 mols) of phosphorus cxychloride and 166 g. (1.37 mols) of dimethylaniline was stirred under reflux for two hours. After cooling to room temperature, phosphorus oxychloride was removed by distillation at 18-22 mm. and 22-37 C. The, residue was then poured into a vigorously stirred mixture of 500 ml. of ether and 500 g. of ice. After separating the ether layer, the aqueous layer was extracted with 500 ml., then 200 ml. of ether. The combined ether fractions were dried over sodium sulfate, filtered, and the ether removed by vacuum distillation at 10-22" C. The residue, a yellow solid melting at 37-38 C. weighed g. corresponding to a 90% yield. Vacuum distillation of 115 g. of this material at 7480 C. (16 mm.) gave 108 g. of white solid melting at 38-39 C. corresponding to an 84.5% yield.

Analysis-Calculated for C HN Cl F: C, 28.70; H, 0.60; N, 16.75; Cl, 42.47; F, 11.38. Found: C, 28.77; H, 0.82; N, 17.01; Cl, 42.25; F, 11.66.

Example 2.2-Chl0r0-4-Amin0-5-Fluoropyrimidine (111) To a solution of 10.0 g. (0.06 mol) of 2,4-dicl1loro-5- fiuoropyrimidirie in 100 ml. of ethanol, 25 ml. of concentrated aqueous ammonia were slowly added. A slightly opalescent solution resulted. The temperature gradually rose to 35 C. The solution was then cooled in ice to 18 C. and thereafter remained below 30 C. After three hours, a Volhard titration showed that 0.0545 mol of chlorine was present in ionic form. Storage in a refrigorator overnight resulted in some crystallization of ammonium chloride. A white sludge, resulting from the evaporation of the reaction mixture at 40 C., was slurried with 75 ml. of water, filtered and washed free of chloride. After drying in vacuo, the product melted at 96.5197.5 (3., yield 6.44 g.

6 well stirred mixture was brought to the boiling point within 10 minutes and boiled an additional 10 minutes. whereby 50 ml. of toluene was distilled off. The suspension cleared up somewhat at first, then a guru separated which finally was transformed into a granular deposit,

' which was separated by filtration from the hot toluene Evaporation of the mother liquors yielded a second 7 crop of 0.38 g., raising the total yield to 6.82 g. (79.3%).

Analysis.-Calculated for C H N ClF: C, 32.56; H, 2.05; N, 28.48; F, 12.88; Cl, 24.03. Found: C, 32.69; H, 2.25; N, 28.46; F, 13.02; Cl, 23.94.

A slurry of 34.0 g. (0.231 mol) of 2-chloro-4-amino S-fiuoropyrimidine in 231 ml. of concentrated hydrochloric acid was heated in a water bath at 9395 C. for 125 minutes. The reaction was followed by means of ultraviolet spectrophotometry using the absorption at 245, 2 85, and 300 m as a guide. The absorption at 300 m rose to a maximum after 120 minutes and then dropped slightly. The clear solution was cooled to C. in an ice bath, then evaporated to dryness under vacuum at 40 C. After slurrying with water three times and reevaporating, the residue was dissolved in 100 ml. of water. To this solution, cooled in ice, 29 ml. of concentrated ammonia were added dropwise. The resulting precipitate was filtered, washed free of chloride with water, then with alcohol and ether. After drying in vacuo at 65 C., the product weighed 22.3 g.

An additional 6.35 g. was obtained by evaporation of the mother liquor, thus yielding a total of 28.65 g. (96.0%).

Analysis.Calculated for C H ON F: N, Found: N, 32.67,

Example 4.5-Flu0rocytosine-Monomercury (V) Hot solutions of 6.38 g. (20 mM.) of mercuric acetate in 200 ml. of methanol and of 2.58 g. (20 mM.) of 5- fluorocytosine in 75 ml. of water were mixed. After cooling to 26 C., 20 ml. of 2 N NaOH were added slowly with stirring. The pH changed from 4.6 to 11.65 and a thick jelly-like precipitate formed. It became filterable only after addition of 200 ml. of methanol and 1250 ml. of ether. The precipitate, separated by filtration, was dispersed in 400 ml. of water, the suspension was boiled for five minutes and filtered hot. A waxy solid was obtained which became powdery upon drying in vacuo at 80 C. Yi ld, 6.07 g. This material, when placed upon moist litmus paper exhibits an alkaline reaction.

Analysis-Calculated for C l-l O N F g: N, 12.16. Found: N, 12.17, 11.99.

A suspension of 3.27 g. of S-fluorocytosine-monomercury (containing 0.9 millimol of combined S-fluorocytosine) in 125 ml. of toluene was dried by distilling ofi about 20 ml. of toluene. After cooh'ng to room temperature 7.76 g. of Z-deox -3,5-di(p-toluoyl)ribofuranosyl chloride was added with stirring to the suspension. The

solution. It weighed 0.96 g. and contained unreacted 5- fluorocytosine determined spectrophotometrically (about 36% of the starting material was recovered).

The toluene filtrate upon cooling deposited gummy material which was separated by decantation. The supernatant solution was washed in a separatory funnel with 25 ml. of 25% potassium iodide solution and then three times with 10 ml. of water. This treatment produced additional gummy material.

All of the gummy material obtained was dissolved in about 20 ml. of chloroform, the chloroform solution was washed with 10 ml. of 25% potassium iodide and then with water, dried over sodium sulfate and evaporated in vacuo. The frothy residue (1.1 g.) was dissolved in 10 ml. of benzene. Addition of 50 ml. of petroleum ether to the well stirred benzene solution produced a precipitate which was first gummy and became granular upon continuous stirring. It was filtered off and washed with petroleum ether. Yield, 0.835 g. It was purified by dissolution in 7 ml. of benzene and reprecipitation with 200 ml. of petroleum ether to give 0.77 g. of a colorless powder (designated A), which comprised impure FCDR (FCDR, i.e. fluorocytosine deoxyriboside, is herein employed as an abbreviation designating a mixture consisting of the ozand fi-anomeric forms-i.e. 2'- deoxy-S-fluoro-cytidine and its a-anorner) The toluene solution, evaporated in vacuo to a volume of about 10 ml, deposited 100 mg. of crystals melting at 183 which were identified as p-toluic acid. The mother liquor upon evaporation gave a partially crystallizing oil (7.22 g.), which was taken up in 20 ml. of benzene and added dropwise with stirring to 300 ml. of petroleum ether to produce an almost colorless precipitate which was filtered, washed with petroleum ether and dried in vacuo. nated (B), also comprised impure FCDR.

For the detoluoylation, 3 g. of the above mixture (B) was shaken for one hour with a mixture of 25 ml. of ethanol and 10 ml. of 2N NaOH. Most of the material went into solution. After filtering, the solution was rendered congo acid by addition of 1.8 ml. of concentrated hydrochloric acid, alcohol was removed by partial evaporation in vacuo and a precipitate of toluic acid Was separated by filtration. The filtrate was extracted with 15 +10+10 ml. of chloroform and excess of chloroform was removed by partial evaporation. The resulting yellowish solution (53 ml.) a =-|0.l7 (2 dm. tube) contained according to ultra-violet spectrophotometry 2.46 millimols of FCDR.

in the same manner, 0.74 g. of the mixture (A), isolated above, gave by hydrolysis with a mixture of 25 The above mentioned solution containing 2.46 mM.

of FCDR was chromatographed by bringing the solution onto a column of Dowex 50-X8 resin 2.5 x 4 cm. an eluting first with water, and then from fraction No. 39 on with 0.02 N ammonia. Flow rate was about ml. per hour and fractions were taken half hourly. The

Yield, 3.21 g. This precipitate, desig:

ultra-violet absorption was measured in samples diluted with 0.1 N HCl at 260, 280 and 300'111 2. The total absorbency at'280 m as Well as the ratios cytosine) in 75 ml. of dimethylforrnamide there was added with stirring 7.78 g. of 2-deo=xy -3,5-di(p-toluoyl)- ribofuranosyl chloride (20 mM.). An almost clear solution resulted in ca. 10 minutes.

2%; and ggg in a Water bath of 4050 C. for one hour, then cooled to room temperature and filtered. A solution of g. were as listed in Table I below. Authentic 2'-deoxy-5 of potassium iodide in 190 ml. of water was added to fiuorocytidine has 9.55 at 280 m and a ratio the filtrate. A gummy precipitate formed. Addition of 280 300 150 ml. of ether brought the precipitate in the ether =3l8 and =099 10 layer. The Water phase was again extracted with 150 ml. and then twice with 100 ml. of ether.- The com- By using these values it was possible to check the purity bined ether extracts were evaporated and gave a dark of the fractions and to calculate FCDR content and oil. This was deacylated by shaking with a mixture of [0 Fractions were pooled accordingly. 30 ml. of ethanol and ml. of 2N NaOH for one hour.

TABLE I FODR Frac ion 2s0 2% 1 [041, 6 Remarks mm. mg.

Starting 23,500 2.11 0.98 2.46 006- +7. 5

Maten 4- 8,450 1.78 0.91 0.875 217. -15.3 contains or and deoxyribose 0 O derivatives. 3.0 1.02 "0105' ""121 free of 01' and deoxyribose. 2.7 0.985 0. 229 50 +1s D0. 2.9 1.02 0. 373 91 +7 Do. 2.3 1.0 0.215 53 positive Do.

Samples of the pooled fractions 11-19, 20-26, 27-45, and 46-47 were chromatographed on paper using the upper phase of a mixture of ethyl acetatezwatenformic acid (12:7:1) (ascending). Only one ultraviolet absorbing spot R;=0.11 was found. Fractions 27-45 showed also a fluorescent spot (R =0). The FCDR anorner content in the spectrophotometn'cally fairly pure fractions 11-45 was calculated at 268 mg. Fractions 11-19 when tested as growth inhibitor of Sarcina lutea, Bacillus simplex, Staphylococcus aureus, Escherichia coli, and Bacillus subrilis exhibited an activity corresponding to a 60-80% content of Z'xleoxy-S-fluorocytidine in the anomeric mixture.

The solution obtained by hydrolysis of mixture (A), containing 1.03 mM. of FCDR, was similarly chromatographed on a Dowex 50-X8 (NHfi) resin column,

A cloudy solution resulted which was rendered congo acid by addition of 34 ml. of N HCl. After removal of some alcohol by evaporation, the solution was filtered and finally concentrated to a volume of 35 ml. Spectrophotometric analysis gave a total 2a0 36,8OO Table II), corresponding to 3.86 mM. of FCDR. Paper chromatography using the system described in Example 5 (Le. upper phase of ethyl acetatezwaterzformic acid, 12:7:1) disclosed, in addition to FCDR, the presence of one or two slower moving deoxyribosides, of one or tWo pyrimidine-free deoxyribose derivatives, and of toluic acid.

The solution was put on a Dowex -X8 (NHJ) column, 100-200 mesh, 2.5 x 44 cm. Elution was performed with water at a flow rate of 150 ml. per hour, fractions being taken half hourly (Table 11).

TABLE 11 Fraction o1 Em 2&2 noon, Br Values 1 Starting Material. 36,800 2.14 1.0 3.85 ODU .101) .01, .7D .00 3 7,080 1.92 0.90 0.74 0D .10D .0D.7D

+ 13,700 2.65 1.0 1.90 013 .osan .10D .01) .7 4,600 2.88 1.0 0.48 01317.10]:U 1,150 2.54 0.95 0.12 .ion

1 The index U designates ultraviolet absorbing, the index D designates deoxyribose con- (Deoxyribose test according to Buchanan, Nature 1951, 1091). ODU and .035 correspond to slow-moving deoxyribosides"; .IOD corresponds to FGDR; .6 and .71) correspond to deoxyribose derivatives; .96 corresponds to toluic acid.

taining spots.

100-200 mesh, 1 x 25 cm., at a flow rate of 30 ml. per hour, fractions being taken half hourly. Fractions 2-13 contained, according to spectrophotometry, 227 mg. of FCDR,

This brought the total yield of spectrophotometrically identified but not crystallized FCDR anomer mixture to 495 mg. 7 I

Example 6 .--2 'Deoxy-5-F luorocytidine To a suspension of 3.27 g. of S-fiuorocytosine-monomercury (containing 9.43 mM. of combined 5-fluoro For further purification fractions 3 and 4 were again chromatographed. Fraction 3 was evaporated to dryness and the residue obtained was extracted repeatedly by boil- 3 ing With a total of 75 ml. of ethanol.

The mixture Was heated TABLE III Fraction o1 E @9 FCDR, R1 Values Starting 7, 020 2.14 1.0 0.74 013 1019 01) .71)

Material 3 98 1.31 0.90 1,140 1. 80 O. 93 .03413U .09313 .191: .5813 .7513 1,215 1.80 0. 91 03413 0913 .5813 .751: 1,000 1.8 0.9 .08 2 -82 181 11075 2: 71 :98 0: 11 i 1 U and D as in Table 11, index F signifies fluorescent. Fractions 31 and 32 contained chromatographically fairly pure FCDR. For further purification these frac- 56 tions were evaporated to dryness and the residue obtained 260 was dissolved in 6 ml. of water. The solution was partly decolorized by stirring with about 100 mg f Evaporation of fractions 7-10 (Table IV) yielded a 1.}{4 (D Ch i l CO Midland, Michigan; an anion colorless glass which was dissolved in ml. of ethanol. exchange resin consisting of a cross-linked copolymer of 20 Upon gr,adua1 0890' petroleum ether to styrene with divinyl benzene [4% of the latter], eon- 51$ "Solution F Standing n the refrigerator, 1 30 mg. of mining (mammary ammonium groups as the functional crystals meltmg at 167-170 were obtained, WhlCh proved groups), 100-200 mesh size, previously converted to the f be F 0 of FCDR anomers' M101- formate form. The solution obtained by filtering from the blologlcal detarmmanon gave a 50% B'FCDR Camemresin contained 30 mg. of FCDR [a] =3O. Accord- "inalysls" calculated for C9H12FH3O4: 44-08; ing to antimicrobial tests, this product contained 25% of 494; N, Fmlndi -5 H, 5.15; N, 16.84, fl-a110mer 16.86. [a] :0.7 (c.=0.3 in water). 0.1 N HCl, Fraction 4 (Table II) was evaporated to dryness, dis- 289 (6 10,700) N 01mm 248 (6 solved in 5 ml. of water rendered congo acid by addition 1370)- of 0.2 ml. of 1.0 N formic acid and chromatographed on 390 a column of Dowex -X8 (NHJ form), 100-200 T mesh size, 2.5 x 44 cn1., water being used as eluant, flow 2 rate 80 ml. per hour, fractions being taken half hourly =3 16 (see Table IV). 260

TABLE IV Fraction 01' E 50 E noon, a, Values 0 Starting 18,700 2.65 1.0 1. 90 ODU .035D .lOD

Material. 61: -7D 3 103 1.3 .79 4 :1: 915 1.7 .93 .033D .11p .61;

Thus, the total yield of chromatographically and spec- EXAMPLE 7 trophotometrically acceptable material composed of the Fraction 6 (Table IV) was evaporated and the residue was dissolved in 5 ml. of ethanol. Addition of 15 ml. of petroleum ether to the alcoholic solution produced a sticky percipitate. To the solution decanted from the precipitate additional 10 ml. of petroleum ether was added.

A gum precipitated which upon trituration solidified. This was discarded. The mother liquor of this precipitate gave, upon further standing, 25 mg. of crystals, M.P. 168-l70 0., which proved to be a not quite pure mixture of FCDR anomers, according to U.V. spectrum and chemical analysis. It contained ca. 50% of fi-FCDR, as determined microbiologically.

AnaZysis.Calculated for C H FN O C, 44.08; H, 4.92; N, 17.14. Found: C, 44.80; H, 4.80; N, 16.90.

mu (5 11,800). 0.1 N HCl, 1 249 m (6 2510).

To a water-free suspension of 3.45 g. of S-fiuorocytosine-monomercury (9.63 mM.) in ml. of toluene there was added with stirring 8.59 g. of 2-deoxy-3,5-di(p-chlorobenzoyl)-D-ribofuranosyl chloride (20 mix 1.). By heating the mixture gradually to refluxing a part of the solids dissolved. The mixture was refluxed for one-half hour, then was filtered hot from undissolved material (11.54 g., containing unreacted S-fluorocytosine). The filtrate upon cooling deposited 2.84 g. of crystals, which were filtered and washed with toluene. This solid contained p-chlorobenzoic acid, identified by its melting point of 237-238 C. after washing with potassium iodide and recrystallization from toluene.

The toluene filtrate from the 2.84 g. was washed with 20 ml. of potassium iodide solution (25 then with 2 x 15 ml. of water, and was evaporated to an oil. This was deacylated by shaking with a mixture of 35 ml. of ethanol and 15 ml. of N NaOH for 1 /2 hours. Some residual gum was separated by filtration, and the filtrate was rendered congo acid by addition of 1.35 ml .of concentrated HCl. Chlorobenzoic acid crystallized out, and additional amounts were separated by evaporation and taking up the residue with 25 ml. of water. The final filtrate was extracted twice with 15 ml. of chloroform, partially evaporated in vacuo and chromatographed on a D0wex 50X8 column, 100-200 mesh size (NH form), 2.5 x 42 cm. Elation was eifected with Water, at a flow rate of from 29 to 38 ml. per hour.

Fractions 13-33 contained 0.5 mM. of FCDR in chromatographically purified form.

I claim: '1. 1-(2'deoxy-3',5' diaroyl-D ribofuranosyl) 5-fluor0- cytosine.

2. A process of making 1-(2-deoxy-3,5'-diaroy1-D- ribofuranosyl)-5-fluorocytosine which comprises reacting 5-f1uorocytosine-monomercury with 2-de0xy-3,5diaroyl- D-ribofuranosyl halide.

3. A process Which comprises reacting S-fiuorocytosine with a mercuric salt, thereby forming 5-fiuorocytosinemonomercury; [reacting the latter with 2-de0xy-3,5-diaroyl-D-ribofuranosyl ha1ide,. thereby forming 1-(2- deoxy-B',5'-diaroy1-D-rib0furanosy1) -5-fluorocytosine; and splitting ofi the aroyl groups from the latter, thereby forming 1-(2-deoxy-D-ribofuranosyl)-5-fluorocytosine.

References Cited in the file of this patent UNITED STATES PATENTS 2,804,459 Drinkard Aug. 27, 1957 2,885,396 Heidelberger May 5, 1959 2,892,840 Tarsio June 30, 1959 OTHER REFERENCES Fox et aL: J.A.C.S. 79 (1957) pp. 5060-5064.

Kissman et aL; J.A.C.S. '80 (Oct. 20, 1958) pp. 5559 5564.

Heidelberger: Nature, March 30, 1957 (vol. i179) pp. 663-666.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,040,026 June 19, 1962 Robert Duschinsky It is hereby certified that error appears in the above numbered patent. requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 8 for "35" read 3,5 line 40, for "5" read 5 column 3, line 9, for "mermuric" read mercuric column 7, TABLE I, heading to the seventh column, for [D read [(113. same table, sixth column,

line 1, for "606" read 606 column 8, line 9, for "precipitate in" read precipitate into column 11, TABLE V, in the heading to the sixth column thereof, for "mm." read mM.

Signed and sealed this 25th day of December 1962.

SEAL) \IICSIZ RNEST W. SWIDER DAVID L. LADD nesting Officer Commissioner of Patents 

1. 1-(2''-DEOXY-3'',5''-DIAROYL-D-RIBOFURANOSYL) -5-FLUOROCYTOSINE. 